According to World Health Organization data, TB remains one of the world's top-ten leading causes of death, killing nearly two million people each year. Multi-drug resistant strains of M. tuberculosis -- as well as even more dangerous, extensive-drug-resistant (XDR) strains of the bug -- are emerging each year.
"Obviously, we are going to require more than the traditional antimicrobial approach to turn this situation around," Dr. Quadri says.
In this study, Dr. Quadri, along with co-lead researchers Drs. Julian Ferraras and Karen Stirrett, focused on particular small-molecule virulence factors called phenolic glycolipids (PGLs).
Various strains of M. tuberculosis use PGLs to weaken our body defenses whereas M. leprae uses PGLs to damage and invade our nerve cells during infection.
"Therefore, we hypothesize that drugs blocking PGL synthesis would reduce the adaptive fitness of PGL-producing M. tuberculosis strains in the human host by eliminating PGL-dependent immunomodulatory effects. These drugs may also diminish the ability of M. leprae to invade nerve cells and produce nerve function impairment," Dr. Quadri explains.
In complex work in the laboratory, the researchers investigated and then elucidated a crucial, early step in PGL biosynthesis. They also pinpointed a key enzyme, called FadD22, that is essential to that stage of the process.
"Based on that, we collaborated with Dr. Derek Tan's lab at Memorial Sloan-Kettering Cancer Center to synthesize a molecule that targets FadD22 and successfully inhibits that early step in PGL production," Dr. Quadri said.
Follow-up work using both enzyme assays and M. tuberculosis assays confirmed that the new inhibitor does block the production of PGLs. Although it was technically not possible to test the inhibitor in M. leprae, that pathogen is very closely related to M. tuberculosis, so the researchers believe their agent would inhibit product
|Contact: Andrew Klein|
New York- Presbyterian Hospital/Weill Cornell Medical Center/Weill Cornell Medical College